In typical computer architectures, video graphics data that is to be processed from an application running on a processor, for example, may either be processed by integrated or discrete graphics processing circuitry. Integrated graphics processing circuitry is typically circuitry integrated in a bridge circuit connected to the processor system bus, otherwise known as a “Northbridge.” Discrete processing circuitry is typically an external graphics processing unit that connects to the Northbridge via an interconnect utilizing an interconnect standard such as AGP, PCI, or PCI Express. In order to further increase the processing resources for video graphics processing, it is also known to utilize one or more discrete graphics processing units working in parallel, all of which are connected to the Northbridge via standard interconnects.
FIG. 1 illustrates a typical computer architecture known in the art utilizing this type of parallel processing. As shown, a main processor 102, such as a CPU or any other processing device is connected to a bridge circuit 104 via a system bus 106. As shown, the bridge circuit 104, which may be a Northbridge, includes an integrated graphics processing circuitry 108, which may be used for video graphics processing if an external graphics processing unit is not connected to the bridge circuit 104. An example of a known Northbridge circuit utilizing an integrated graphics processing circuitry is ATI's Mobility Radeon® 9100 IGP integrated graphics processor sold by ATI Technologies, Inc. of Markham, Ontario, Canada.
The architecture of FIG. 1 also illustrates at least two external or discrete graphics processing units 110 and 112 connected to the bridge circuit 104 via respective interconnects 114 and 116. These interconnects 114 and 116 may comprise any known standard bus including AGP, PCI or PCI Express. Additionally, the discrete graphics processing units 110 and 112 may be configured such that one processing unit connects through the other processing unit to the bridge circuit 104. This is shown, for example, by dashed line connection 117, where interconnect 116 would not be present (also indicated by the dashing line 116).
Currently when an add-in card, such as GPU 110 is plugged into an AGP, PCI or PCI Express slot connected to the Northbridge circuit 104, the processing circuitry 108 in the Northbridge 104 is not utilized and only the external graphics processing unit, such as GPU 110 is used to perform processing of graphics data. Accordingly, the resources of the integrated graphics processing circuitry 108 are usually not utilized and, thus, wasted.
Moreover, as discussed previously, it is known to employ parallel processors, such as GPU 110 and GPU 112 in order to increase the processing capacity and band width of the system 100 in order to deliver processed video and graphics to display media 118, which may include one or more monitors, PDA displays, cell phone displays or printers. Although the utilization of multiple graphics processing units (e.g., 110, 112) increases the system processing capacity, existing processing circuitry 108, as mentioned above, cannot be applied to the same graphics job, and potentially is unused when one or more external or discrete processing units are connected to the Northbridge circuit 104. It is noted that a graphics job, for purposes of this application, refers to a number of tasks, such as graphics processing or display operations, that are performed in conjunction to produce a display. For example, a graphics job could include multiple tasks such as vertex processing, 3D rendering, and driving the display that are performed in conjunction with one another to produce a display.